Arbutus

a small genus of shrubs belonging to Heath tribe, natives of northern temperate usually evergreen, and broad-leaved. The or sub campanulate, white or pink corolla, rethat of the lily-of-the-valley, is deciduous, the five-chambered, many-seeded ovary forms berry-like fruit. A south-European species, A. the Strawberry-tree, grows perhaps indiat Killarney. The scarlet, strawberry fruit is edible. Arc, 4 continuous curve joining any two points. is longer than the straight line joining them, is called the chord. The length of a circular is proportional to the angle subtended at the and to the radius of the arc. [CIRCULAR | Arc, ELECTRIC, obtained by sending a sufficiently electric current from one carbon pencil to To start the action, as the extremely resistance of the air spnce between the points prevent the pa age of the current, the points must be made to touch and then be drawn apart. A little of the carbon is and so forms a conducting medium the poles. Its electrical resistance is so con however, that the temperature becomes high, the carbon poles are rendered white hot. an intensely brilliant light is emitted. Gold platinum are readily vaporised, and diamond into black amorphous carbon, by the heat of the arc. In arc lamps there are or other arrangements for regulating distance between the two carbons, so that the may not fluctuate as the pencils are burnt away. LIGHTING, INCANDESCENT LAMPS. ] Arca, the Ark-shell, a genus of LAMELLE- (q.v.), of which several species occur the English coasts. It is the type genus of the a family which has existed since the Low period. 192 Arcachon. ( 176 Arcachon, a fishing village and health resort in the department of the Gironde, France, about 30 miles west-south-west of Bordeaux, with which it is connected by rail, and on a large, almost landlocked, basin that serves as a harbour and a site for numerous oyster-beds. ‘The dry, sandy soil of the Landes, the mild climate, and the vast extent of pine forests have caused Arcachon to be frequented by consumptive patients in winter, whilst visitors from the large towns of the south flock thither in summer for sea-bathing. There are several good hotels, a4 casino, and all the other attractions of a French watering-place. Axcade, « series of arches upheld by pillars or columns, either open or closed by masonry behind. A more modern use of the term applies it to any gallery or pa age lined with shops, as the Bur. lington or Lowther Arcades, The term is again applied to the row of arches or piers dividing the aisles of a church from the nave.